1. Field of the Invention
The present invention relates to a tank holder for detachably holding a liquid tank, a liquid tank mounted to the holder and a method for attaching or detaching the liquid tank with respect to the tank holder.
2. Description of the Prior Art
There has been conventionally proposed a recording apparatus for recording on a recording medium such as paper, fabric, plastic sheet or OHP (overhead projector) sheet so as to be capable of mounting a recording head which applies various recording systems including wire-dot system, heat-sensitive system, heat-transfer system and ink-jet system.
Among various types of recording apparatus, an ink-jet recording apparatus is utilized as a printer serving as an output terminal of output means for information processing system including copy machines, facsimiles, electronic typewriters, word processors and work stations or a portable printer included in personal computers, host computers, optical disk devices or video devices.
An ink tank for supplying an ink to a recording head has a container for accommodating an ink, an ink absorber for absorbing and holding the ink and a cover for sealing the container.
Examples of the recording head include an ink tank-integrated recording head which is configured integrally with an ink tank and an ink tank exchangeable recording head in which an ink tank is detachably provided.
Because of improvements in reliability of recording heads and low running costs, an ink-jet recording apparatus which uses an ink tank exchangeable recording head cartridge has been recently utilized widely. In particular, in order to correspond to color printing, an ink jet recording apparatus to which a plurality of ink tanks (e.g., two ink tanks for black and color (cyan, magenta, yellow) or four ink tanks for black, cyan, magenta and yellow) are mounted is accepted in the market.
In the case of the ink tank exchangeable recording head cartridge, positioning the relative position of an ink tank with a recording head for the purpose of reliably supplying an ink from the ink tank to the recording head is an important matter for recording quality.
For this reason, it is important to realize compactness and to obtain a structure which is operated more simpler, has a simpler mechanism, eliminates disadvantages at the time of attachment or detachment and does not decrease the precision of positioning.
In an ink tank included in the above-described conventional ink tank exchangeable recording head cartridge, a protrusion which is engaged with a removal preventing hole of a tank holder is provided at its lower end of one side surface abutting the inner surface of the tank holder. Further, this ink tank is provided with a latch lever having a latch pawl engaged with an engagement hole of the tank holder at the other side surface opposite to the one side surface with the protrusion provided thereon. When the ink tank is mounted to the tank holder, the ink tank is rotated with respect to the tank holder about the protrusion engaged with the removal preventing hole of the tank holder, and the latch pawl is engaged with the engagement hole. As a result, the ink tank is mounted to the tank holder. When the ink tank is removed from the tank holder, it is rotated with respect to the tank holder about the protrusion engaged with the removal preventing hole of the tank holder, and the lower end portion of the one side surface with the protrusion formed thereon abuts the inner surface of the tank holder, so that the latch pawl is disengaged from the engagement hole (see Japanese Patent Application Laid-Open (JP-A) No. 10-286972 (document 1) (page 8, FIG. 4)).
An ink tank included in another conventional ink jet cartridge is provided with a second pawl engaged with a second hole of a tank holder at its lower end side of one side surface abutting the inner surface of the tank holder. Further, this ink tank is also provided with a movable lever having a first pawl engaged with a first hole of the tank holder at the other side surface opposite to the one side surface with the second pawl being provided thereon. When this ink tank is mounted to the tank holder, it is rotated with respect to the tank holder about the second pawl engaged with the second hole of the tank holder, and the second pawl is engaged with the second hole. In this way, the ink tank is mounted to the tank holder. When the ink tank is removed from the tank holder, it is rotated with respect to the tank holder about the second pawl engaged with the second hole of the tank holder, and the lower end portion of the one side surface with the second pawl being formed thereon abuts the inner surface of the tank holder, so that the first pawl is disengaged from the first hole (see JP-A No. 2000-127425 (document 2) (page 4, FIG. 3)).
Nevertheless, the above-described conventional examples have the following problems.
In accordance with a portable printer, the entire printer is required to be made as compact as possible. Thus, an ink tank and a tank holder must be also configured compact. Consequently, a space required for detaching the ink tank from the tank holder must be even further small.
In order to prevent an ink supplying tube of the tank holder from interfering with the bottom surface of the ink tank at the time of removing the ink tank from the tank holder, an ink supplying port of the ink tank must be large or be provided so as to be apart from an engagement protrusion.
For color printing, four color inks, i.e., cyan, magenta, yellow and black inks are required. If there is a relatively large space, independent ink tanks for these four color inks are desirable. Nevertheless, a portable printer usually comprises two ink tanks, i.e., a black ink tank and a color ink tank (which is an ink tank with accommodating chambers for three colors, i.e., cyan, magenta and yellow) because its compactness is demanded.
In particular, as in the aforementioned color ink tank, when three accommodating chambers are formed by dividing its inner portion into three parts, it is preferable, in view of its usage, to equally diving into three accommodating chambers so as to have the same internal volume. This is also preferable in view of its manufacturing because common components can be used. Nevertheless, when an ink tank with relatively small capacity is attached or detached as described above, it is always significantly difficult to accomplish the same time the structure for forming three accommodating chambers with the same internal volume and the structure for preventing an interference with an ink supplying tube.
In accordance with the above-described conventional recording head cartridges, when an ink tank is removed from a tank holder, a space in which the top surface portion of the ink tank rotated with respect to the tank holder is moved is ensured within the tank holder. For this reason, in conventional tank holders, in order to ensure the aforementioned space, the upper end side of its peripheral wall is formed so as to be bent externally of an ink tank. This results in a large tank holder and thus a large recording head cartridge (see documents 1 and 2).